Hi Emma - and dealing with your queries in turn:
1 The letter itself should suffice, and no-one should need to contact your mother. Explain this to your IP to make sure that no-one calls.
2 Salary increases are usually taken into account with end of year reviews, at which time you also have the opportunity to adjust your expenditure as well which will increase with inflation.
3 Make sure that you do not accept any increase in payments that you do not feel you can afford. Best to be honest with yourself at this stage and look to another solution, than "jumping from the frying pan into the fire" with an unaffordable IVA payment.
Regards, Melanie Giles, Insolvency Practitioner for over 20 years.
Appoint me as your IP:
http://www.melaniegiles.com/ivaEnquiry.asp