Keep records of everything. All payments to them, all calculations for uplift. When sending uplift, email them the payslip and ask them to let you know if they don't agree with your calculation (i.e. no reply needed if they do agree).
If you are waiting on them for the outcome of a review or similar, keep the ball in their court as much as possible. Just like in business
Whilst waiting, regularly email about progress. Remind them to let you know if they need anything from you and that you are still waiting to hear from them. Word it in a way that needs no response unless they do need something or have news. That way, their lack of replies can later be used as evidence they needed nothing and had no news.
Keep all automated responses as proof the email arrived.
If they do ask anything, reply as soon as you possibly can, do not delay.
If you do all the above, when they do finally get their act together and come back to you, it places them in a VERY weak position to make demands, especially urgent ones or back-payments etc...
I don't think they will be playing nasty, I really don't. This is just about playing safe
