Three cars are believed to have been used in the latest attack this evening, with the raiders leaving one hanging half-way out of the building as they fled in the other vehicles.
It is not yet known what goods the thieves have taken.
A police spokesman said a cordon was now in place around the shop, in Vicar Lane, after police were called shortly after 9pm today (August 20). The road is open to traffic.
He said: "We had quite a few calls about a ram-raid ongoing. It would appear there were three cars being used: a Nissan Qashqai, which is still in the shop, a BMW X1, which we believe has been used to leave the scene, and a red car."
It is the third time in nine months that the designer store has been ram-raided.
Thieves struck in December last year and again on June 25.