Perhaps someone will correct me if I am wrong, but my understyanding of this current problem is this:
There are just a few sources of the gas supplied which are used for domestic (and industrial) heating and cooking purposes. Once it is present in this country, there is a single national storage system supplying a single nationwide network of delivery pipelines. Every gas user obtains a gas supply from this system.
However there are (or were) dozens of companies - large and small - whose whose business activity is to be a gas "supplier". They install a gas meter in each of the properties they "supply" and then the user obtains gas from the single national network. Apart from obtaining a periodic meter reading and issuing a bill for the quantity of gas used, the "supplier" plays no role in the obtaining and distribution of gas.
Apart from collecting money for a product with which they have no physical contact, do these companies provide any useful service? Is this business structure more effective and efficient than a single national company? How, except in the process of sending bills, is there any competition here?