Received a bill for 2 invoices from Purolator that...

Received a bill for 2 invoices from Purolator that were supposed to be paid by the company I do contract work for. The company neglected to deal with it and now I'm stuck having to pay it and submit an expense report for it instead. Wouldn't be a problem if they had maybe a website to process these transactions, or agents assigned to the cases that actually picked up their phones. Not saying that these invoices don't need to be paid, I'm saying I literally CAN'T pay them until one of these folks calls me back. Not even their reception answers phone-calls and this is within working hours.

They also backdate their letters. They claim to have sent me something on July 23 but I received it on August 13? Yeah... that seems legit... If you're past the 10 days they say you could incur late fees and they'll submit it to ruin your credit. If they submitted literally anything damaging on this one, when they clearly backdated it so I couldn't respond in time they'll hear from my lawyer.