Vendor never billed me for work done

[Bienes Raices]

I had extra insulation put in the attic of the rental house almost 2 months ago. It was about $500 worth of work. I there & ready to pay with a check at the end of the job but the workers said they didn't have a bill for me and that I would receive one in the mail. I waited a month and didn't receive a bill. I called their office and asked about it and I explained to them they need to send the bill to my address, not the rental house, etc. She told me she would send the invoice to me, she just needed to speak to someone else in her office first. Now another month has gone by and I still haven't received anything from them. Should I just forget about it?