Trying to get a bill from Calor Gas

punto123

Moved into a new property Nov 2019 (19 plots on the development, LPG tank underground to services all plots for gas ) , first or second week of moving in rang Calor to set up account with them, they where confused saying we do not supply the address,  and new nothing about the site , so that call ended, tried again few weeks later no luck ,I thought I would wait for the occupier letter to come through from them, like one did from BG informing they supplied the electric and to set up account, but nothing ever has , Have rang the developer a few times , the said would look into it, nothing came of that , calor a few months ago came out themselves to take gas reading, told them i have not had a bill , heard nothing , about a month ago meters read again by a 3rd party on behalf of calor  told them i have not had a bill , heard nothing.

I assume when calor ever get round to sending a bill they are within the right to ask for full payment in one go for the past year ?
Am i right to assume i am under no obligation to contact them and ask for a bill ? I have no problem  paying the bill , but after the efforts made above , i don't see why i should spend anymore time contacting them if they can not be bothered as a business to keep their accounts up to date  , and which properties they supply.
Having spoking to a few neighbours, some have been able to set up an account and others have not , and also had no bill.
Surely the onus is on them to contact customers  and produce bills not the other way round 
Many thanks for reading and any input