HELP!! Depositing money into my account

Summer

So I have a medical bill with let's say ambulance company a (not actual name just using it in this scenario) and I pay my bill online. I recently looked at my online banking account and ambulance company a deposited 202.02 into my account I there is no item saying they withdrawed that amount so they're not returning money that they accidentally withdrew. I still owe 298 dollars so I know i didn't accidently pay more than what I owed, so I'm not sure why they are depositing money into my account. There isn't an ID on the bank statement for it just has the company name on it.