Upgrade AP to include MM, told me they couldn't do over the phone

Need some clarification since I don’t want to spend extra money that I don’t have to. I purchased an AP back in September prior to the free photopass inclusion so I tried to call up and find out A) Could I upgrade the AP I have now and B) if so how much would it cost. Disney told me I couldn’t upgrade over the phone and could only do it at Guest Services in the parks. Now I don’t mind doing that but they couldn’t tell me how much it was so now I am a little nervous to go an not have the MM already set up since I will lose the $169 price if for some reason the AP upgrade does not work. Can anyone help with prior experiences and what I should do?

I upgraded at the parks. I had renewed in May and upgraded in October. The cost was around $86 for the upgrade.

However, if you’ve pre-purchased MM already and it’s linked to your account, it won’t be refunded if it’s been activated (if you’ve already taken a pic in the park or on a ride). At least that’s what the CM said to me when I was upgrading and had asked about getting a refund.

So if you already have purchased MM, be sure to do the upgrade BEFORE you get any photos done.