IMHO, Metro man and Ndicho Moja got it right. The only reason expat contracts exist is for temporary requirements. Contract renewal is not an obligation, if the company continues to require your services, they will offer a new contract, up to you to accept.
I think arguments along the lines of "if it wasn't for expat pilots.........." shows immaturity. You were contracted for a job, you did the job well, thank you very much. Here's your pay according to what we agreed in the contract. Unfortunately, we will not be requiring your services any longer and therefore will not be offering you a new contract when the current one expires. We hope you had a pleasant stay and wish you all the best in your future endeavors.
Nobody got stiffed. What's there to gripe about?