unless the debtor has the cash ready to pay, most debtors never, ever respond (and shouldn't) to any actions to collect debt by a third-party collector, so that there is no chance at the even tiniest appearance of acknowledgement.

often, even if you have the intent to pay the debt, paying to any agency other than the originator of the debt is risky. debt collectors roll over debt en masse to keep them legally fresh and will not honor any promises that haven't been duly signed and served.

Contact from a third party collector? Sure, don't respond. But if you're being summoned by the court under threat of a default judgment then you should probably show up or don't be surprised about the outcome.

for sure, respond to the court.

you can often find low-cost, non-profit defense organizations to help if needed.