Following up on a letter

I did a dumb thing this year (of all years): I mistakenly filed an estimated tax payment made to the IRS as a state payment in my tax software.

My State figured it out right away, and sent me a letter saying "You goofed up, here's what we calculate, we're reducing your refund, if you agree you don't have to respond". That's fair.

I received a LTR 12C letter 5 weeks ago asking for more information before the return could be processed - probably because the information on my filing didn't match theirs. I responded to it right away with all the requested information, including proof of the estimated tax payment that I forgot to include on my return, and I have USPS verification that it arrived in Kansas City.

So, given the current situation, how long do I wait until I follow up? This is the first time I've had to respond to a letter like this. In a normal year, I would probably try to get them on the phone about now. But how much longer should I give them?

(Also, does it matter which number I call? I note that the form lists a separate 800 number for business owners, and this estimated payment was made on self-employment income.)

Thanks!