XLP Document Solutions NOT GOOD FOR PAYING FOR SERVICES THEY REQUEST

We have recently rendered a service to XLP Document Solutions after the director approved the order form, now that they have to pay for the services the lady in accounts is making so many excuses not to pay. The amounts and payment method is on the form there is no way has a director you would miss this. This company seems to want work done for free. Even though we have the order in black & white they are behaving unprofessional.