Leaders Merchant Services Leaders Fraud, asking me to alter invoice and holding funds Thousand Oaks California

This company was ok for a while and all of a sudden they are holding funds and hanging up on me. When I finally get through they are asking me to alter an invoice. The customer who paid me with a visa says they called him and wanted to know if we completed the job. He told them he was very satisfied with our work and to release the funds. It is going on two weeks and we haven't received a large sum of money we desperately need to keep our business running. I have contacted a lawyer and I will have to sue now to get my money. Please stay away from this company. They had good reviews when I started with them and now they lie, lie, lie and ask you to fax altered invoices and use stall tactics like voicemail and hanging up.