Deep packet inspection

Forgive me if I sound ignorant and overly suspicious, but is it possible for online retailers who offers there own financial services to monitor and divert packets at will? What I am asking is this; I attempted to make an online payment recently and the financial website was down, or so I thought. I tried from three of my home PC's and each time I received a error page saying the site could not be reached. I then tried from my work laptop which was connected via VPN to our corporate network and I was able to access the financial section of the retailers website and therefore make my monthly payment. I checked online to see if others had posted complaints about the same thing and I was amazed at the number of people having the same issue. So, here's my question, is it possible for a online retailer (with who I and countless others have used their registration feature to register our PC's with them)to monitor outbound packets from account holders who are trying to access their financial website to make a payment and return a error page instead of linking us to it?, thereby causing us to be late on making our payments and accessing us late fees in the process?