Acer plant - growing advice

I bought an acer plant last year, but unfortunately at the end of the first summer only 2 twigs were growing. My initial thought was that the rest of the plant wasn't growing due to some kind of infestation. So back in May I trimmed the the 2 twigs that had grown excessively long right down, and sprayed some insect repellent ond the remaining bit of the acer. But here we are in September and exactly the same thing has happend again.Any suggestions?