<human>: Can you give me the gist of the text in a nutshell?

I have recently resigned from my job in order to take up a new job for various reasons, mostly to do with a slight shift in career focus but also because I'm feel my soon to be ex-employer isn't really going anywhere.

Anyway, the point of this post ... I've just finished the first year of a 2 year part time Masters degree which my to be ex-employer has funded so far.  I originally approached them about this hoping for them to pay the fees upfront and for me to repay as a salary sacrifice.  As it turned out, they seemed quite keen on paying for it as the subject matter was relevant to their industry.  My University raised an invoice and they paid it in full last year.  No written agreement was ever reached and no expectation for me to repay was insinuated.  There is a clause on my contract regarding them being able to withhold my pay if I owe them money but nothing regarding training costs being repayable.

Roll on this week and I'm one week in to a 1 month notice period and I find I've not been paid my last months salary until I agree to repay the years tuition fees in full from my final two paychecks.  It is less than my final two paychecks but will leave me financially screwed and barely able to cover my rent and food.

My new employer, although unaware of the situation, is willing to bring forward my start date so my employment is covered.

I'm just not sure what to do now.  I've not been paid for the last month and I've had to draw on my credit card to pay the rent.

Do I threaten a tribunal?  If I did, might that have an impact on my future career (e.g. background checks etc)?  Am I totally wrong and I do owe them this money?
<bot>: My employer has been funding my degree and I've handed my notice.  They now want me to repay the course fees in full and immediately and are withholding my paycheck.  There is no written agreement.