Not available, still waiting for refund

Wish there was a 0 stars
Ordered a matterss cover on line for click & collect.Next day received an email stating "Hi Customer,

We are sincerely sorry to advise that the Fast Track order you recently placed was not successful and as a result your item(s) will not be available in-store for you to collect. A full refund will be issued which will require no further action from you. If you haven’t received your refund in 7 working days, please contact your bank.

If you have any questions please visit Argos Help where you will find answers to many frequently asked questions, product information and all our full contact details
We apologise for any inconvenience."
Please NOTE: " A full refund will be issued which will require no further action from you. If you haven’t received your refund in 7 working days, please contact your bank."
Nearly 3 weeks on, no refund. After a fight with their Chat service was advised the order HAD NOT BEEN CANCELLED, did I want it cancelled.
Having confirmed cancel, told it would be a further 5 days (at least) before refund MAY BE received.
Seems a reguar complaint on their website, more than happy to accept payment for items they don't have BUT very reluctant to refund when it's their fault!
Perhaps they should have to pay a penalty fee to customers, that would speed things up!