Greetings! You are correct that the phrase "Te dije que venía y vine" can be translated as "I said that I was coming, and I came" in English. This translation helps distinguish between "venía" (I was coming) and "vine" (I came), making it clear that you communicated your intention to come and then followed through with that intention.
Your initial attempt, "I said, came and came," is not a clear translation because it doesn't convey the distinction between the two Spanish verbs. Your revised translation, "I said that I came and I did it," is also a valid way to express the idea, but it's slightly less precise than the first translation in capturing the verb tenses.
So, "I said that I was coming, and I came" is a good way to convey the meaning of the original Spanish sentence while differentiating between "venía" and "vine" in English.