Collection debt

Please help! Last year back in October I got a letter from the collection company stating I have some debt with the hospital 2 years prior. But I don’t think I still own it. So within 30 days I emailed the dispute to the collection company and requested prove evidence within the next 30 days. Time past and I never received anything from them, now March of 2025 which is more than 30 days of the initial email I sent them, they sent the a letter stating what services I was receiving.

So in this case what do I have to do next? I thought the debt was already disputed cause they failed to respond?

Thanks