Upgrade from Basic to Plus

Hi, I have recently purchased to stock up cameras as an addition to my doorbell. I have a current Protect Basic covering the doorbell (renewed in June XXXX), and as the trial for the stock up cameras is ending I’d like to upgrade to Protect Plus to cover all devices. When I chose to upgrade on the website, it asks me to pay the full price for the Plus plan and it does not take into account the money I have already paid for the Basic. Is there any way to recover the money I have paid, or at least some of it? I suppose I could cancel my existing plan, but I wonder if that is the only option… thank you!