Can Someone Explained Mortgage Holiday Repayment Increase Cost, I Don't Understand the Maths

Genex

Hi. I've been looking and reading about corona mortgage holidays, but I'm confused as to why the repayment increase is as much as it is. 
So lets say I'm paying £550 a month at 1.99% on a 20 year 1 month mortgage (241 months about £132,000). I've been told that my repayments would increase to about £558 a month from then on. 

What I don't understand is that equates to £1,928 additional payment (£8 x 241) on missing 3 months which is only £1,650 in total.

How does being charged interest only for 3 months equate to £1,900? When that is more than my mortgage is in total with repayments AND interest.

What is the maths used to calculate it. Surely the total repayable should be the 241 months I have left as normal plus 3 months worth of just interest?

RelievedSheff

The interest is based on the mortgage balance not your monthly repayment.

Thrugelmir

Over the 3 months that the holiday lasts. You'll not pay around £660 of interest. This £660 will be added to your outstanding mortgage balance. Resulting in you having to repay £132,660 over the next 241 months. The difference btween £1,928 and £660 is the additional interest you'll incur. By taking the holiday and deferring repayment. Holiday is a misleading word as far from being cost free. 

Genex

Thank you, I think I get it now. I assume any remortgaging packages will just work as usual in the future, this one is fixed for 4 years