Dyson V15 Vacuum Battery Not Charging

Six months ago, I bought a Dyson V15 vacuum cleaner, and it used to charge just fine. But it stopped charging recently, even though it showed that it should be charging. I took it to the service center, where they told me that I needed to replace the battery. After ten days, the new battery seemed to fix the problem, but it didn't last long. The charging problems with the vacuum started up again. Since this appliance costs a whopping 2,700 tl, I was expecting it to work well and be reliable. We chose Dyson, especially because we have pets, but we really regret this purchase.