Katie,
As has been said you haven't provided much information such as how far in to a bond were you, did you leave by choice etc. However many years ago an employer airline, when relocating us from one base to a new base, paid estate agent, house removal etc. fees and it was 'proposed' we would be bonded for 2 years decreasing by 25% every 6 months, unfortunately, for them, the airline proposed this but neglected to get us to sign anything.
When I subsequently resigned some 10 months later the union backed me on the basis that I hadn't signed anything and I hadn't profited because I was moving home again, at my own expense, to take up my new job.
In your case you say it was for, including, operator line training, OPC, company safety training, these are operator specific, legally required, trainings, whilst you take the experience you cannot transfer operator line training, operator proficiency check etc. between operators, these are operator specific, the operator MUST provide these to you, OK you took however many months of your LPC remaining with you but your next employer, presuming you were moving on to operate the same aircraft type, probably renewed your LPC during your initial training, your previous LPC check might have been something that you never used after leaving.
So what did you gain out of this, what did you take away from the company that you could use thereafter, a few months of an LPC and a piece of paper of few regarding wet ditching etc, all of which have a limited shelf life before they need renewing. As for hotels, meals and petrol etc, is it your fault that the company couldn't provide your training at your designated base whereas you could have eaten and slept at your home?
Overall it depends on the scenario, i.e. did you quit weeks, months or years after receiving all this training but my argument would be that very little of this training can be, was, taken with you, you didn't utilise it after you had left thus you made no financial gain thereafter from being provided with this training.