Clients receiving CP 14 and CP 503 for balance due when IRS has cashed their checks months ago

[lbones]

I have several clients that are receiving notices for payment for balances that have been paid.  Have sent documentation to the IRS with backup (with copies of canceled checks) but still the letters are coming and clients are getting nervous.  Have tried the hotline but have not been able to get through.  Any suggestions?  Client see CP 503 referencing seizing their account and are getting upset, I don't have the answer to calm them down. 

[Just-Lisa-Now-]

Yes, it seems that the computers that send out bills aren't directly connected to the computers that process payments....there must be some kind of manual processing in play with these or something, Ive seen a few of them, Ive done like you, send a copy of the canceled check, my mother-in-law has sent it 3 times now, fingers crossed 3rd times a charm.