Eddie I sympathise with you..................these leeches are simply trying to screw you. Putting you on a bond is possibly reasonable, but paying for line training most certainly is not. As K M says, you are operating revenue flights, so should not get any reduced compensation.
Asking for money up front, plus a bond, plus reduced income whilst training, sounds like they want three enormous bites of the cherry.
Good on you for taking a stand, and also for telling others of this situation.
Just for the information of your readers, can you say how much experience you have on the 737? Plus how much turbine and multi-crew? Not trying to embarass you, just get an idea of whether Transmile's assertions about experience have any shred of credibility.
Hope you find something else soon.