They emailed me saying I reached the "weekly threshold" which they themselves dont know the threshold amount as its build into the system. Also said i would need to wait for 7 days before being able to perform any transactions again, which clearly isn't the case as i was able to pay a different merchant earlier.
Conclusion is they can impose any restrictions as they like and wont provide you with any resolution. Very unreliable as you wouldn't know when the "weekly threshold" would be met. I have been very cautious by topping up only what i plan to pay into the wallet, but this this happens