Well, I thought it would be worth resizing the axes on the chart in that spreadsheet:
There are so many columns on there it's hard to see what's what, but apart from that really bad 174ms spike at 18:27:39, whilst quite a few numbers aren't great (10ms+) they're not catastrophic either (I'm assuming everything is in ms!). It might be worth you trying to group the same measurement from multiple devices together on their own separate charts (one for physical read, one physical write, etc) - it's a bit tedious but shouldn't take too long.
Other than that you need more external information. What are normal response times for this time of the day/month/quarter/year, what it is that makes someone say that the performance is bad, statistics (like AWR) from the database about what its measured response times are, and so on. You need to build up a full picture of the problem and system interactions to try to see what area the problem lies in (it is easy for people to point at the database and say it's slow when it may be a result of something completely different).
Good luck!
Message was edited by: Simon.H - to add image from file instead of inline