Superfast plan 78% Increase in Monthly cost, from $50 to $89

My monthly bill for the Superfast plan went from $50/month (including a $10 credit for autopay), to $89/month. I don't know why the increase is so high. 

What is the best cost/month that Xfinity can offer me? There are other ISPs available to me that offer 1000 Mbps for $80/month.  I am considering moving to another ISP.