Online broadband upgrade offer rescinded

I upgraded my broadband from 350 mg to 1gb yesterday. The price was very similar to what I was paying already I.e £42. I got all the confirmation through etc confirming everything and then today I get an email asking me to call the sales team as they needed some information from me. Upon calling they said I had been misquoted and that the price was actually more. Whilst on the phone I actually tried to upgrade again and was quoted exactly the same price as yesterday. Felt like I was being called a liar. Not sure the girl I spoke to actually understood what I was saying and she put the phone down on me after I asked to speak to a supervisor. My contract ends in October and was hoping to get a decent deal before it ends but if this is how I am treated I am sure there will be other companies out there I can use. It will be a shame as I have used virgin broadband for 20+ years. Don’t advertise my upgrade offers and then try and charge me more for services than quoted.