Somebody must to explain this to me:

A = supplier
B = importer
C = customer

Price development:
A = 1,00
B = 1,20
C = 3,00

We are B (importer).

Today received e-mail from supplier.

Supplier said: We (supplier) will not do business with you (importer) anymore, because you (importer) work directly with our customer..............

Can anybody explain the logic to me..................??