My IVA started in May 2018 and I started off paying £159.12 A month, in 2021 this went up to £282 A month and in May this year they increased it again to £314. My salary has increased slightly but not drastically and my I&E hasn't changed much either. My initial debt was £18000 and is due to end in May 2023, is it worth asking for a re-evaluation with only 7 payments to go?
At each review your provider should have given you the figures to agree. I would be inclined to ask for copies of each calculation, with explanations as to why the increases occurred, as a first step. If they are wholly inaccurate, you can then challenge them.
Be aware that a challenge at this stage will, more than likely, hold up the due completion, especially if you win the argument and any overpayments need to be clawed back from creditors.
To my mind, you have weathered the storm and are close to the end. You will still not, or should not, have paid more than the original debt plus interest that would have been due without the IVA, so are still on top. You owed around £18,000 plus ongoing interest charges and will have paid just shy of £13,000.
I am not qualified to give advice and can only state my opinions, based on my IVA experiences.