Pa Municipal Service Co Billed me twice for the same thing stating that I need to remit more for the same total bill to be paidpaid! Pennsylvania

 Last month 6/16 I called the company and asked if I could make online payment and thought it strange they couldn't take a payment of area taxes! So I paided the amount not wanting to get in trouble due to their name. I paid the amount in full! Now this month 7/16 they are back asking for more more showing my last payment but stating another total due requesting more money and threaten penalty sending back a installment agreement stating that more maybe be owed but they don't know what's owed! Wanting me to sign a agreement to pay them after I just paid a bill that was suppose to be paid in full.