You may already know this but…

There’s a 30 day rule on eBay for returns/disputes etc

Personally I have had about a 99% positive eBay experience over the years

But there was one seller who, with the benefit of hindsight, was clearly fobbing me off and procrastinating until the 30 days were up. I didn’t know about the rule at the time, and it caught me out (it wasn’t a bicycle, but obviously the same rules apply etc)

By all means give them a chance to put it right, but don’t give them too long, and consider logging an official return sooner rather than later

Best of luck mate - it happens to the best of us