Tesla described 2018 as the “most pivotal year” in their history as the automaker was able to sell nearly 140,000 Model 3s. This means the car was the best-selling premium vehicle in the United States last year.

Tesla was able to achieve this despite problems at the Gigafactory and issues at their production plant in Fremont, California. The problems have largely been worked out, but the flood of new Teslas is creating issues of its own.

According to the Wall Street Journal, the rapid increase in production has exacerbated the company’s notoriously slow repair process. In essence, more Teslas on the road mean there are more Teslas getting in accidents and needing to be repaired.

Tesla owners have struggled with long waits to get replacement parts and it appears the issue hasn’t gotten any better. The publication talked to one Model 3 owner who had to wait for three months to get a replacement bumper for their car.

Bumpers are pretty common replacement component and a three month wait is staggering. Tesla forums are also peppered with reports of long waits and the issue goes back several years.

Unsurprisingly, the delays have been met with frustration and anger in some cases. This is understandable as getting replacement parts from other automakers is a pretty quick and straightforward process.

Tesla is aware of the issue and the paper noted CEO Elon Musk has stated his top priority for this quarter is to improve how the automaker services its vehicles. Of course, this won’t be an easy process as a lack of replacement parts can’t be fixed overnight. However, Tesla sales have shown signs of softening so more parts could be directed to repair centers.