However, if you have a separate contract for the storage unit rental and it's not on the premises of the residential rental unit, then it may fall under storage unit rental laws.It's paramount that you invoice in a timely manner whenever a tenant owes you for something.

I sent them an email stating all of my concerns and asking for invoices and proof of items that were fixed.

She is a bit hot now , her boyfriend tells me " we need 3 estimates " Sorry , all I have to do is give you is a copy of the invoice Why cant you do the work to save me money ?      

Solve this by invoicing the tenant and use a cover letter to explain he recovers for the EX. 

They just send me the invoice for any job under $150 once they're done.Does it cost me a bit more money?

Judge might ask for proof of invoice for your original cost and age of carpet.

I agree with @Travis Spar (dang link thing never works for me).  

I would do it and then bill them for usage (add it to the rent and include an invoice).

For the rest, I'd make an appointment for them to see the unit, letting them know that the first approved tenant who actually signed a contract and paid the security deposit got the apartment  & that I kept showing the unit until that is what I had.And if they were late (without a call with a dang good reason like they're stuck in bumper to bumper traffic, which I could verify on Google maps) or didn't show, they were denied.  

I asked for the invoice and when I received it they didn't give me an itemized bill.