I go to the mikvah every day in the early morning before anybody comes. I pay a monthly fee. Normally the floor is clean, but many days the floor was not cleaned it is very sticky. Since I get infection on the button of feet if not clean, I take a clean towel to put underneath. The mikvah charges a dollar for the extra towel. I am wondering if I am not entitled to a free towel for two reasons, first when paying for the mikvah I expect the floor to be clean specially right in the morning. Second for the past thirteen years I do not go there Erev Shabbos and Yom Tov which till now adds up to more than 650 times. don’t I have a credit?
You have to pay for the extra towel that you take unless you get specific permission to use a second towel. True, the mikva should be cleaned, but a clean mikva is not a monetary obligation of those running it, in the sense that they now owe you the value of a clean towel. Therefore, make sure to pay for the extra towels. If you would like, you can ask the owner of the mikva if you can use some of the used towels to stand on, which they might agree to easier than allowing you to use a towel for free.
The fact that you didn’t go on erev Shabbos doesn’t give you credit, because you are paying for the privilege of using the mikva for the month, and after that, it expires.