Tfg sterns

Good morning I bought a set of watches at sterns canal walk on the 3 December 2019, I then returned it on the 29 december 2019 because both mechanisms were faulty was told at that time that the supplier is closed, which I then understood. With written proof that I was there I returned to the store on 09/01/2020 then I was told that the items had to be repaired and not replaced.

I first had a slight disagreement with the store assistant as to why I can't have my money as it was within a thirty day period as to the (CPA Act), up until today they giving me a major run around telling me that I have to wait for the technician to give feed back before they can do anything for me,

I have the book in slips that stipulated that there are no physical issues only internally. What can I do from this point onwards.