When I had an ERP & CRM Reseller business, most customers were reasonable but a significant few were bullies. I found the best way to deal with them is to be to

When I had an ERP & CRM Reseller business, most customers were reasonable but a significant few were bullies. I found the best way to deal with them is to be tough back, to say no to unreasonable requests, to charge even more than to other customers and remind them that they are always free to go elsewhere, I had several screaming swearing calls as a result, but the strange thing is, they rarely left and they paid in full.