Most customers have a handle on bringing reuseable bags to the supermarket now, Sue Allen says.

OPINION: It's time to shame Countdown and New World into stopping talking and actually doing something about getting rid of plastic bags.

Their commitment to phase out single-use plastic within 15 months is, I've decided, a ridiculously long time frame.

Why have I come to this view? Because I'm beginning to feel like I'm being played.

ALDEN WILLIAMS/STUFF Fifteen months seems like a ridiculously long time to phase out plastic bags.

I'm constantly being bombarded with info, promo and ads from New World and Countdown talking about how great it is that they are going plastic bag free.

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But instead of talking, they could just do it.

SUPPLIED Sue Allen: ''Neither company has a choice. Consumers all over the world are demanding change.''

Last week, there was a NewsHub interview with Duncan Garner interviewing its "partner" Countdown about ending the use of plastic bags.

The interview ran side by side with the company's own video using cute kids telling their parents off for not taking their own bags to the supermarkets.

Meanwhile, New World is all over my social media feeds proudly partnering with a host of celebs as part of its "Bags Not" campaign.

Frankly, neither company has a choice. Consumers all over the world are demanding change.

There's a huge risk to the brand value of both of these chains if they don't ban the bags, and they know that. Yet it's still going to be another eight months before it happens.

So here's something for supermarket customers to chew on as they wait for December 2018 to roll round - the date both chains have said they will go plastic bag free.

Countdown's own figures say it uses 350 million plastic bags a year.

So, let's do a quick tally of the number of plastic bags which will have been given out by Countdown since it started thinking about doing something, as opposed to actually doing something.

There was the two years of research Countdown did talking to its own customers to find out if they "were ready" to go plastic bag free; so that's 700 million single-use plastic bags given out before it made a solid public commitment to act, which it did in October last year.

Add to that the 435 million more plastic bags Countdown will give out in the 15 months between October 2017 and December 2018.

We're now up to 1.1 billion single use plastic bags in circulation before something tangible happens.

It would probably be a fair guess to say New World gives out roughly the same number of plastic bags each year, so let's add on another 435 million bags from the date of its announcement to action. That's a lot of plastic bags.

Baffled by the delay, I looked into the reason why it was taking so long.

Credit where credit's due, at least Countdown made it easy for me to locate its reason for taking 15 months to act. New World; not so much.

Countdown's reason: "The transition will take 15 months, as we talk to our customers about change, re-develop our check-outs and introduce better and cost-effective alternatives."

Come on. Countdown, you've already said you'd been talking to customers for two years; we can all see that supermarket customers have found "cost-effective alternative" bags; we are all happily using the same totally un-changed checkout queues with our new eco-sacs; and supermarket staff seem to be coping just fine.

What I am seeing is both companies filling a lot of air time, and doing a lot of brand building, as they ride the wave of public interest on this issue without getting on with something that's just not that hard.

So, Countdown and New World – to borrow words from another well known campaign – ''Just do it".

Sue Allen has worked in journalism, communications, marketing and brand management for 16 years in the United Kingdom and New Zealand.