to talk about things that we managed to do on specific occasions in the past, we cannot use could. Instead, we use was/were able to. The verb managed, succeeded (in…ing) are also possible in this case.
I was able to get some really good bargains in the sale. (NOT I could get some really good bargains in the sale.)
After climbing for several hours, we managed to get to the top of the mountain. OR After climbing for several hours, we were able to get to the top of the mountain. (NOT … we could get to the top of the mountain.)