Bad apprenticeship experience- what to do now?

Hi,
I started a leisure apprenticeship this time last year and just finished this last week. This involved me doing a lifeguard course (would cost £250 if I wanted to do it on its own) and then getting put on a full time shift for a year earning £140 a week, doing the same as everyone else on a much higher wage just with the tag of 'apprentice'. I also got £50 deducted from my first wage to 'cover training costs' (which I believe may not be legal?) The shifts are evenings and weekends included on a rolling rota, either 6-3 or 1.30-11, averaging at 39 hours a week.

I have just finished this and got told I won't be getting taken on full time due to there being no spaces available and instead going to be taken on casually. However, I am aware that they are taking on a load of new apprentices, coincidentally starting on the same day that I was due to finish and I've also had a look at the job advert for this and it advertises them as earning £308.88 a week which is well over double what I was on. Also, there is going to be barely any casual shifts available in the coming month due to uni students coming back, new apprentices starting and new part time staff meaning that I am more than likely going to struggle getting work. Please note that not getting taken on full time is absolutely nothing to do with my own performance, as I have had 0 sick days in the year, 0 disciplinary's and I even got nominated for 'apprentice of the year' last year. Also I was still on the rota's to continue working after I was meant to finish until I took in my contact and showed them so I'm not immensely happy with the way it has been handled.

Just unsure of what to do now really as this seems a bit wrong, don't want it to seem like 'I'm not getting my own way so I'm going to complain' but it doesn't seem quite right, especially with the new apprentices getting paid almost a full wage compared to the 3.30 an hour I was on. just after a bit of advice really! Thanks.