How do I combine items with different names?

If you don't care about the name at time-of-sale, but only want to plot current name, then there's no need to deal with a type 2 SCD. Type 1 would be sufficient (how you track in the source is irrelevant to how you handle in the analysis and presentation layers).

If you can utilize [CustomerID] for all of the relationships in your model that have to do with customers, you can just store a single value for [CustomerName] in your customer dimension.

You can utilize SQL or Power Query to find the most recent name for a given [CustomerID]. If it's not important to preserve a specific, most recent name, you could even take a shortcut by using the 'Remove Duplicates' transformation in Power Query - this would non-deterministically remove all but one [CustomerName] associated with each [CustomerID]. It may even be deterministic with an appropriate sort order (unsure how the transformation is implemented in PQ).

CraigBlackman Since you have the account_id, I'd just create a mapping table which will be your dimension. Each account_id and the company name like greggyb suggests. 

You could easily create a process after the initial table creation to check / add new companies going forward. (based on the assumption that the initial company name would stay going forward.)