Lost cheque

I paid in a cheque on 7th December 2022 at my local shop/post office in Long Sutton, Somerset. It has not been received by my bank which denies responsibility because these items are just sent through the mail like any other. I rang Royal Mail which also denied any culpability as the "post office is a separate company and they send the stuff in pouches." How, I enquired? By Royal Mail, I would surmise but the man I was talking to didn't seem to know.
So, I the customer, trusting a service offered by the Post Office and despite the fact that I have a receipt can't find anyone who takes any responsibility. Well, we already know that Royal Mail is a mess and it would seem that this service offered by the Post Office is unfit for use among the many other things the post office is not fit for. And I would hazard a guess that the poor unsuspecting customer doesn't know the difference between dealing with the Post Office and dealing with Royal Mail. The cheque was for £73.25 and I want it refunded.