Identify the unfair aspect with respect to the sentence extracted from an online Terms of Service:
```
any promotion code or offer provided by us may not be used in conjunction with any other promotion code or offer , past or present . 

```
. OPTIONS: ["Jurisdiction", "Choice of law", "Content removal", "Limitation of liability", "Unilateral termination", "Unilateral change", "Arbitration", "Contract by using", "None"].