Beautiful PowerPoint visualisation

Description

Please note that the budget is a likely maximum, not the exact payment for this work - we will work on an hourly basis and decide on an hourly rate in advance. Thank you!
I work for a healthcare market research agency in the UK. We are creating a 10 - 15 slide PowerPoint deck to be used by our client to present some key data points to senior management.
The topic of the PowerPoint deck is perceptions of doctors on a treatment our client manufactures.
When the contents are finalised by us, I am looking for a graphic designer who specialises in PowerPoint to:- Update the visualisations - clean, clear and visually striking. Within this there will be one 'killer' slide that can be used as a one-pager- It is likely that there will be up to 3 rounds of edits - our client is very picky and they tend to not know what they like until they see it!- With this in mind, the successful person will need to be flexible and open to feedback
As with all our client projects, there may be a higher or lower number of slides than the 10 - 15 specified above, but it is unlikely to be more than 20 - so the scope of the project may flex, and we would of course increase the number of billable hours.
I would like portfolio examples of clean and visually impactful PowerPoint slides that incorporate numbers (bar charts, line charts), with key story elements / text.
The colour palette and font (Corbel) will be set as it needs to match our client's branding.
The successful person will need to sign an NDA.