I was explaining the difference between a wholesale price for broadband and the amount an end user pays for their "infinity 2". The wholesale price is a small part of the whole picture.

Absolutely. You just used a wrong value for "line rental"

I try to work out with line rental and isp which I put Plusnet to add profit, support, other things to add on before selling to the customer below:

FTTC 80/20 £38.99 pm (inc line rental)
FTTC 160/30*** £46.98 pm (inc line rental)
FTTC 330/50*** £51.99 pm (inc line rental)

***FTTC with G.Fast