"Make sure you get them to map out any discounts, don't fall for any arbitrary models. They are not trying to rip you off, but they have to make a profit." Put simply, users want agility as the business changes while vendors want predictable returns.

Baty said customers need to understand the vendor's business model, his first tip was to allow the vendor to make enough money. He also suggests finding the right balance between trust and control so that long-term deals are based on solid relationships.

Also, when putting out a tender make sure it is attractive to a broad range of vendors and includes the incumbent.

"Vendor relationships are like marriages; once you are married you must keep talking and communicating," Baty said.

"Often you find out more about the vendors you are not using, because they are pitching for business, than you do about your current supplier. "Keep up the dinners, the dialogue and get to know people behind the scenes; keep the marriage working."