We get a number of questions about how discounts and data promotions
are applied to O2 tariffs and why it appears not to be added to the account.
In order to help, I've created a small guide.
First thing to note is that your MyO2 http://www.o2.co.uk/myo2 will always display the full tariff price before any discounts are applied. This is what most customers see and assume they aren't getting any discount. (You will see the discount when your bill is generated. Until then it will always show the full price.)
O2 apply your discount as a bolt on (yes I know it sounds backwards) but this bolt on actually credits your account with your applicable discount.
When your bill is generated, the discount is deducted from the tariff price shown in your MyO2, so if you have a tariff of £18 and a bolt on for a £3 discount, your bill will be £15 etc.
If you look in the tariff section of youor MyO2 https://mymobile.o2.co.uk/paymonthly/myallowance/allowance?disambiguation_id=d95778d4-82dd-4087-bb9c... you will see your discount all being well, as per this example below.
In addition, if you have one of the data promotion tariffs, ie a base tariff of 3gb which has 12gb due to a promotion, this will also be shown by the addition of a data bolt on.
You MyO2 will show that you have 3gb only though and the additional data will kick in when the 3gb is used.
You may also get warnings of using all your data after using the 3gb, but don't worry about this as it's just an automated system message.