Bad service

Good morning I have a problem with AHK Spares in Eersterivier, I bought a car battery for my Jetta 5 20TDI in September 2023 that's still under guarantee. I took the battery back to them and they said they check it out. This morning this Womba salesperson call me to say I can collect my battery they not replacing the battery. Please advise what can I do in such a situation. Thanks Victor