If you face a long wait in the queue at your local parcels office to pick up a missed Christmas delivery this weekend, spare a thought for those living in one part of south-east London who say they have endured months of postal woes after Royal Mail closed their depot.

Lost bank cards, letters taking a month to arrive, several days between deliveries and, most frustrating of all, 60-minute waits in the rain to pick up parcels that could not be delivered: these have all been endured by East Dulwich residents who are furious that Royal Mail appears to be failing to provide the service it is legally obliged to offer.

But it is not just an issue for East Dulwich. Since it was privatised, Royal Mail has shut more than 50 delivery offices and more closures are threatened as the company seeks to reduce costs.

If your local office is under threat, you had better hope the process is better managed than the Dulwich debacle, say many in south London. In September, and despite a long campaign by the local MP backed by residents, Royal Mail closed its Silvester Road depot. Postal deliveries are now sorted and delivered at a much larger depot in Peckham, which is a 30-minute walk away. Undelivered parcels have to be collected from there too.

The problems started almost immediately after the switch, say residents. They say they are lucky if they get one delivery a week. Important documents including a number of bank cards have gone missing. One Dulwich resident says six bank cards sent to her household have all failed to arrive. Postal workers have admitted to customers that they don’t have time to complete rounds, meaning some houses go unvisited for days on end.

Those unlucky enough to miss a parcel delivery must head to Peckham to collect their items – an hour-long trip by bus – where they then say they face waits of up to an hour. They describe a chaotic office that was unable to cope even before the Christmas rush got going. Affected residents have bombarded Royal Mail bosses and their MP, Helen Hayes, with complaints.

Money reader and Dulwich resident Serena James says the postal service in her area has collapsed. “Residents go days or even weeks without receiving any post at all, and countless items never arrive,” she says. “Numerous residents, including me, have had replacement credit and debit cards never arrive, only to find they have been used to make contactless payments in the Peckham area. When packages do arrive, they have sometimes already been opened. It has been utterly chaotic from the start. I have complained to Royal Mail, who claim to be investigating, but nothing is improving.”

Facebook Twitter Pinterest Festive parcels are moved at the Glasgow Mail Centre in Springburn. Photograph: Andrew Milligan/PA Wire/Press Association Images

A long thread on the East Dulwich Forum site reveals the scale of the problems. Residents say valuable items have been left on doormats all day in full view of the street. Some report giving up on home delivery and asking for items to be sent to their workplace instead. Others use courier firms.

Hayes says: “It has been a complete shambles, and is exactly what we predicted when we originally fought the closure of the office. Royal Mail would not listen and this has been the outcome. The nearby West Norwood office is also under threat of closure and, if that goes ahead, I predict the problems seen in East Dulwich will be dwarfed by that. Royal Mail needs to learn from this and think again.”

A Royal Mail spokeswoman said: “At Peckham, we do believe the situation in the customer services point has improved. It is the busiest time of year and there are many more people picking up mail than normal. We have a dedicated manager working in the customer service point all through the festive season.

“Fifty-two offices have closed since privatisation, less than 4% of our delivery office estate. On average, that is around 12 offices a year, which is broadly comparable with the closures pre-privatisation.

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“During the period since privatisation, letter volumes have declined by around 12%. Because letter volumes have fallen, from time to time we have had to close delivery offices. But the number of offices we have closed is significantly less than the decline in volumes. Delivery office closures are entirely unrelated to privatisation. They occurred in state ownership too. Royal Mail has by far the largest delivery office network in the UK and that will continue to be the case.

“Royal Mail has to relocate offices from time to time, and there are a number of reasons for this. Sometimes leases expire and are not renewed.

“Often it is driven by the change in the profile of the mail we deliver (more parcels, fewer letters) which means some of our delivery offices are no longer fit for purpose. Delivery offices may not, for example, have enough space to store parcels, or to park the vans we use for deliveries. Facilities for our people are sometimes not right for a 21st century workforce.”

In its 2016/17 annual report, Royal Mail said it was committed to “reducing the number of facilities while ensuring [it has] the most accessible delivery office network in the UK.” At that time, it had about 1,400 offices.