Unable to find a resolution to my problem regarding the closure of my landline number-966-12-6489871 Saudiarabia-Jeddah

Sir,
It has been more than 4 years that we have made a closure of the landline provided by STC.Now they have sent an invoice for about 21000 riyals asking us to pay for no fault of ours.I have been running around various offices of the STC but all of them says that they cannot help me directly and it could be with the STC call center for business 909.I had made 3 requests at the call center and till date no proper resolution has been given by them.I had also written a mail to their manager at sahafa office jeddah and he too has not replied to my mail.I would be pleased if you can assist me to settle the matter at the earliest and oblige.My contact number is 0558575330.
Landline number regarding- 966-12-6489871 AL Khawaji Perfumes