BoostUp Payment Gone?

Hello,

I purchased an iPhone XR in Feburary with BoostUP payments (said I was eligible). I paid the down payment, and then at the end of the month also paid the phone monthly price with my service ($35 plan + $33 BoostUp! Payment = $68) which was correct, however this month, on my account it shows to only pay $35 for the plan only. Where did the phones monthly cost go? I don't want to get in trouble for not paying.