Corporate Law Prior Vendor Contacting New Vendor? Legal?

[ojnaot]

We were once doing business with company 'A' and purchasing products from them for resale. They then decided to terminate our relationship for reasons unknown and they will not disclose. It was NOT due to nonpayment or anything such as that. We then began to do business with company 'B' which sells the same products that we can purchase for resale. It has come to our attention that company 'A' has begun contacting company 'B' and advising them that they should not do business with us either. Is there anything illegal going on here? Or are their grounds for a case?