I have an existing account with an Austrian bank that provides for a certain level of annual turnover and with a certain kind of payment card. The bank also offers a "higher level" type of account that has higher limits and comes with a better, more universally accepted debit card.
I'm trying to write an email to the bank that contains the simple sentence "I would like to upgrade my account." But I am struggling to find an appropriate German verb for this kind of upgrade. Google Translate suggests "aktualisieren" which seems to imply "update" rather than "upgrade", e.g. bringing software up to the most recent version as opposed to consciously choosing a "better" version of something.
If I give Google the specific phrase "I would like to upgrade my bank account" then it suggests "aufwerten", but dictionary translations seem to suggest that this implies more of an "appreciation in value" rather than the sense I'm looking for.
Any suggestions for what would sound right to a native speaker? It's not the kind of thing one can tell the nuances of just by looking in a dictionary.