Lufthansa refusing to honour quote from iOS app

The iOS application is quoting me 105EUR to add a 3rd bag to my trip however I receive an error when trying to complete the transaction. When I call Lufthansa support, the want to charge me in excess of 200EUR. Lufthansa will not honour the rate quoted by their app. The call center agents refuse to put me in touch with a manager and refuse to provide me with any support with regards to different prices, other than to say that their price and the apps price should be the same.