If you think the fuel charge is uncalled for, now that fuel prices have sunk, you can attend a board meeting and bring this up as a challenge. Better yet would be to talk to neighbors about this.
You should investigate though, because there may be another possibility: If your board is failing to collect monthly fees from some shareholders, or has a heavy debt because of liens or unpaid past fees, they may be taxing unfairly the debt load on the paying shareholders. That is cause for concern, and yes, it might be improper if not illegal. Getting on the board is essential to having the power to change things. Maintenance seldom goes down, but if you can change other rules in the bylaws, such as flip taxes, it can defray rising costs. If you need help, contact Member Services at the Urban Homesteading Assistance Board, or UHAB. They help shareholders ensure their buildings stay in financially healthy positions. We offer free training on record-keeping and can train boards to keep better account of expenditures.
Typically increases are yearly and yes they may add a heating surcharge if the heating season utilities (oil and electric) charges are excessive for the building; usually it is mentions this fact the "by laws" .Consider it a cost of ownership increase, so keep extra cash available in the winter time just in case.