It is the retailers full responsibility during the first 30 days to give you a refund or a new replacement, under the consumer Rights Act 2015. Then for the next 5 months the retailers are still to whom you should go and they should put matters right and, if reference has to be made to Manufactures under terms of a guarantee, it is for the retailers to do so. After 6 months have elapsed from date of purchase there is still a liability for the retailers to put issues right, but not so straightforward.
https://www.which.co.uk/consumer-rights/regulation/consumer-rights-act#:~:text=Under%20the%20Consumer%20Rights%20Act%20you%20have%20a,the%20date%20you%20take%20ownership%20of%20your%20product.
Incidentally, all local Councils have a Trading Standards Department and is able to be of assistance in cases such as your.
Don't be fobbed off, which is what the shop would like. Be polite and let the shop know that friends are telling you that you shouldn't have to contact the manufacturers at this stage.
Best wishes. I hope you are able to get matters resolved.......Hans.