There are a few major reasons your mobile payment may not go through, or why you may have received only some of the RP you intended to purchase.
If you don't respond to each confirmation message in the purchase process, the purchase will expire. In order to make a purchase, you'll need to initiate a new transaction and respond to each message.
If your mobile account has a monthly spending limit and the RP purchase would put you over it, the transaction will fail. It's also possible your account doesn't have enough money to cover the cost of the entire transaction.
Payment not delivered
Disruptions in your network may prevent one or more messages from sending. In this case, the entire mobile transaction will fail. Make sure you're in an area where you can send and receive texts, and that there are no outages in your area.
Partially completed mobile payments
Mobile payments can occur across several purchase confirmation messages. If you begin a purchase and don't confirm each message, you will be charged for a partial amount of the payment without receiving any Riot Points.
If you've been partially charged, send us a ticket and we'll reward you the appropriate amount of RP. To avoid this issue in the future, make sure you're responding to each confirmation message during your purchase.