Failing to deliver what we bought online

I bought golf 6 crankshaft last year October 2022, they sent a wrong one after waiting for it 2 weeks I called in, they asked me to return it, with a hope of quick exchange, 2 weeks went by, I had to call again to query the delay they told me they don't have it on stock they will refund me, whole entire November my refund was not processed, I was forced to open a case for ***** with my bank only then my money was refunded, now with a hope that experience I had last year was unfortunate I bought few car parts 2 weeks ago, when I call in querying about delivery, they told they don't have few parts on stock, I asked why they advertised thinks they don't have, I did not get a straigh answer, I'm still fighting to have my money back or parts that I ordered.