We often hear in Buddhism that we should never make an enemy. Additionally, we should turn enemies into friends.
Essentially, we need to turn, and this will be ever so slowly at first, the relationship around. It's the first turn that's the hardest. It starts with what we tell ourselves about the other person. We try to still the negative chatter and replace it with something positive. Also, we look for their suffering. We replace our frustrated, complaining thoughts with those that are empathetic and caring. Then we'll be ready.
During your next interaction with the person, look for something they do for you that you can label "kind." The kindness may very well not have come from a kind intention. The other person may have been thinking that you're so inept that she needs to do something for you or you'll mess it up! That's okay. What matters at this point is not the other person's intention, but rather how you choose to interpret their action and react to it. By choosing to focus on the kind act instead of the unkind intention, you have the opportunity to react out of kindness. And so you say a sincere thank you.