Hi Sonny!
Your IVA won't end early unless you manage to pay your full original debt, plus statutory interest if applicable, and the fees of the arrangement too. Any income reviews that you are required to pay will be used to improve your creditors dividend, and paid to them in addition to your monthly contribution.
Rather than your creditors "renegotiating" your debt to £19,000, it's better to think of it as them accepting that you can only afford £19,000 during the 5 years and then agreeing to write off the rest. If you can afford more than this during the IVA, then you will be expected to pay more.
Take care!
