First, please carefully check that you have bought the right kind of subscription. Next review the full cost and any discounts and compare those with what is published by your club. If you spot specific differences this should be brought to the attention of the club membership secretary.
If the club is transitioning members for the first time to ManageMyMatch it may be that ManageMyMatch has been unable to ascertain your current subscription status and some discounts may or may not be applied as appropriate. Again, if you think this is the case please contact the membership secretary.
Whatever the circumstance if an adjustment needs to be made in your case this is perfectly feasible as their are procedures by which this can be done.