Liability for the repair of water leakage from an upper apartment

We were told that there was water leakage coming from our unit and the below unit has complained. There was no water leakage found in our unit during the inspection. The technician said his engineer will decide.

A week later, the FM engineer from Al Shirawi called my husband and threatened us to quickly proceed with rectification works and our unit is fully responsible for paying all the costs.

We have requested them in emails to justify that indicated in their 1-page report - hacking bedroom tiles, new bathroom floor and grouting work. They have not replied to justify why.

OA Menu has a RULE 6 clause 6.5 on a shared cost factor. Up till now, the OA Manager from SAGA Intl. kept on insisting that our unit is to pay all costs including any third party testings.

He also demanded me to furnish a copy of the POA to him as I am the one who replies to the emails. My husband is the owner and we are staying in the unit. Does the OA Manager have the right to ask for the POA and ignore the OA Menu on the shared cost clause?

Many thanks.