You are there for a temporary time only. They will let on that your performance will earn you a full time position. But they only take on so many people for small orders from their clients. Once the contract is fulfilled, we are all laid off until the next order comes in.
During this time, you are treated like (bleep) because they know you need the job, thinking if you stick it out, you will get hired on full time and they know in 1-3 months you are gone anyways so they dont care.