Arrear Arrangement

I am at a loss of words for this company. I was unemployed and and now subsequently employment and doing the correct thing, I emailed Izwe Loans in order to make payment arrangements on my arrears. I am unable to take calls during the day as I work only nights and am never awake during the day also, I prefer to have everything in writing. I have set out my proposal in writing and was met with 6 missed calls and an email telling from Izwe consultants telling me that I need to pick up my phone in order to discuss the payment arrangements. I am always working and also overtime as I have a lot of arrears to catch up to. In this century what is the big deal about making the arrear payment arrangements in writing, surely for record purposes this should be acceptable.