Had this last year, 4 year contract was up and I was paying £19 for airtime and 20gb of data. Checked EE and they could do the exact same amount for £8, so I told O2 I was leaving and asked how much EE were quoting and I told them, they just straight up said the best they could do was £15 and have up. 😂 Was with them for a similar amount of time as you.