Has anyone gone from Maxis to a lower priced Hotlink Postpaid plan and kept their number before?

I am on an old Maxis Talk & Surf Principal 1 package at RM 38 and wish to switch to Hotlink Postpaid 30.

I contacted Maxis via Whatsapp and they told me I cannot because the plan is only for new registration, port in or conversion from Hotlink Prepaid plan.

Thanks