I've been on long-term disability with my former employer's insurer since 2017. Recently, I was approved for Canada Pension Plan Disability (CPPD) with a retroactive payment. The insurer adjusted my monthly amount by the CPPD payment and claimed I was overpaid during the retroactive period, billing me a substantial amount. My questions are: Can they deduct the entire monthly CPPD amount from my disability payment? Are they entitled to the entire retroactive payment? If so, do I need to pay it in a lump sum, or can we arrange a payment plan?

Thank you for your time and assistance; it is greatly appreciated.