doctor's billing dept causing over the limit fees on credit

I owed my allergist ~$100 from office visits not covered by my insurance. They asked if I could set up a plan to pay monthly. I have in writing that our agreement is they are to bill my credit card for $20 on the 13th of each month. They have instead been billing my credit card on the 30th of each month. In June my credit card had not much available credit remaining and so they paid the allergist and I incurred an over the limit fee of $18.

I went to the office today and neither the office manager nor the person who does the billing was there. I explained my situation to the receptionist and she said if you are going to have $20 billed on the 13th why wouldn't you still have that money available on the 30th. I tried to explain that I have multiple people who I allow automatic deductions to my card because it is easier than mailing checks. I don't go back to see if all the deductions are charged, I just look at available balance to see how much I have left that I can spend. If I am going to have to check the deductions from the car insurance, the allergist, the hospital bill, my loan repayment, et cetera I may as well mail checks. I expect them to follow the agreement and part of that agreement is which day of the month they can charge my card.

I think the allergist's office should reimburse me for the $18 because they did not follow our written agreement. I am sure if I wrote a check that did not clear because of insufficient funds they would charge a penalty. It works both ways, I think.

Somebody is supposed to call me from the office later this week. Do you think I have a reasonable expectation that they cover the penalty or no?

I wouldn't trust the card's available balance because that is usually a day or 2 behind (like if you charge gas on Monday, it may not get posted until Wednesday or Thursday). When I use my card, I attach a sticky note on it to keep track of what I have spent. Be careful too if the day you plan for a debit falls on the weekend because that may change when the charge shows up. Another thing to try is to have your payments taken out of your checking account. Then you can keep track with the check register.

I'm afraid they will not cover the penalty because they took it out after the day you agreed. If they took it out before that date, you might have a better chance.

When I check my account balance there is a category for 'pending' charges that have not been paid yet and those are deducted from my available cash balance.

When I want to see how much money I have available I don't check to make sure all my payment agreements are paid because all of the automatic payments that I have set up are to be charged before the fifteenth of the month. So if they charge on the last day of the month I am not anticipating that and it screws my system up.

Why bother to even have an agreement to bill my card on a certain day if they are going to throw a dart at the calendar and bill my card then?

I think it was out of line for the receptionist to ask you this question; it's none of her/their business how you manage your finances, they incorrectly billed you and owe you $18 as a result. Tell them to pay up (or take $2 next time as their payment) or you will have to rescind their right to automatically bill you and you will pay them in another way, of your choosing.