IGEN cuts me off, because of their system failure. How do I get compensated?

I requested an upgrade. Had to make numerous calls to get it activated. Paid upfront for better Router and the job. Then, when paying Invoice (at old rate), I called and asked if I should "just add" the difference and was told to 'wait for a pro-rata-invoice". Paid the Invoice, but not the balance (as I was waiting) and yesterday, they cut-off my Service. They have people by the ***** and it has to stop. ???? I even called-in, to pay them and they do not send the additional Invoice AND then cut me off. They actually have some Credit belonging to me on the old plan, and I actually only owe them the "top up". Still waiting. it really is annoying!!