Your supplier is obliged to give you timely, and in any case 30 days in advance in a transparent and comprehensible manner, of any intention to change the contractual conditions and of any change in the prices of the energy supply, both upwards and downwards. Your supplier must inform you of your right to terminate the contract, without notice and without charge, before the change comes into effect. The right to terminate the contract, however, only applies to changes in the energy price itself, but not to increases in other elements of the bill such as taxes or regulated tariffs for the use of the network.
If your supplier does not comply with these formal conditions, you must first send a written complaint to the supplier before you can refer the matter to the ILR under the mediation procedure (you will find a specific tab on this issue on the ILR website).
You can also take legal action to have your supply contract terminated or, as a first step, contact a consumer rights organisation (e.g. the ULC).