Absa insurance does not cover mechanical failure.

About 2and a half year ago ABsa replace my gate motor. InnJune this year the motor stopped working. I could see there is oil running from the motor. Absa declined the claim, because the motor was damaged by the oil. After having a heated argument with them they appointed a new assessor. Now they claim the gate is to heavy for the motor. My question was, so why did Absa in the 1st place install a small motor if they knew the gate is to heavy? Then they changed the clain is denied duento mechanical failure, the policy do not cover mechanical failure. It took them 2 months. Please just let me know who to contact to cancel all my insurances with Absa.