The wording of the clause is not a particular concern because even if you believe they should have said ‘the latter of’, its absence does not make the clause invalid.
As far as the law foes, employers can spend a considerable amount of money on training their employees, only to see them leave shortly afterwards. In order to ensure that the employer can provide an employee with training and that the employee does not take advantage of the situation by leaving soon afterwards, it is common practice to have a repayment provision in the contract of employment. Under it the training costs are deemed to constitute a loan to the employee, which becomes repayable if they leave their employment within a certain period after the training completes.
Whilst it is legal to have such clauses, employers must be cautious to ensure that the amount of costs they are trying to recover is a genuine pre-estimate of the damages which they have suffered as a result of the employee leaving early. In the event that it is not, such clauses could be considered a penalty against the employee, which would make it legally unenforceable. Therefore, if the employer has derived some benefit from the employee undertaking the training course during the fixed repayment period (e.g. where an employer has been able to charge customers more employee’s services by virtue of that training or qualification) then the amounts which may be recovered from the employee should be reduced to reflect that benefit.
The contract should also contain a sliding scale of repayment whereby the repayment amount reduces according to the length of time the employee remains with the employer after the training has been completed. , 100% of the fees to be repaid if the employee leaves within 0-12 months after the training has finished, 50% if they leave 12-24 months after, 25% if they leave 24 - 36 months after.
There are a couple of ways employer to try and recover these fees - by deducting them direct from the employee's wages or, if the employee has already left and paid up fully - by taking them to court.
Any deductions from the employee's wages can only lawfully take place if there was a clear written agreement by the employee allowing the employer to do this, such as a contractual clause or a separate agreement which they signed. In the absence of such an agreement the deduction will be unlawful and can be recovered.
If the matter goes to court, it would be employer to show that the repayment clause was reasonably drafted and that the costs they are trying to recover are reasonable in the circumstances.
One consideration is why you were forced to leave. There are circumstances when an employer has committed a serious breach of contract first. The whole contract, including the clauses on repayment, could then become immediately void and the employee would be treated as being 'constructively dismissed'. So if there are reasons to believe the employer has acted in breach of contract, whether a breach of an express contractual term, or other breaches such as bullying, exposing the employee to unreasonable stress, discriminating against them, etc this reason can be relied on in order to leave and argue that the repayment clauses should not apply.