Sometimes the boost is just not possible to complete as it depends on your performance also. Let's say for example that you are a Silver or Gold division player that want's to duo queue all the way to Grandmaster. At some point around 3800+ SR, it will get really hard to be carried by 1 booster, sometimes even two. Your skill rating gain per win also largely depends on your performance and you can reach a point where 2 wins are giving you a total of 50SR and 1 loss is costing you 60SR. If this happens you always have 3 options to choose from:
1. Pay extra and add more boosters to the party.
2. Convert the boost to account sharing, you will get to a higher level as the solo service is generally cheaper, but you will have to share account details with us.
3. Get a refund for the remaining part of your order.
In all the 3 scenarios, just contact our 24/7 live support to make the changes to your order.