water leaking into cabin

[st.john]

Hello chaps/chapesses!
Firstly a big thanks to all the advice put up on this forum, it has helped massively.
I have just brought a 1998 a6 saloon 1.9 tdi. Great car etc but there is water leaking into the Cabin.
I have narrowed it down to the drains having checked pollen filter etc. Specifically the heat proof matting around the exhaust system is saturated and having cleared it and cut the bit that was clogging up away (about a 2 inch strip) and sealed a hole (not rust, just a plate that doesn't appear welded for about half an inch at the join-whether intentionally or not) and the the flow is down to a tiny trickle- but still there. It is entering the front footwell via a small triangular hole in the front left of the footwell (i can take a picture of needed).
Any ideas what else I could do??
Thanks in advance.

[NickPicks]

Have you removed the battery and cleared the drain holes under the battery and the brake servo? Once those are clear, water should not be able to collect and trickle through the bulkhead.

[st.john]

Have you removed the battery and cleared the drain holes under the battery and the brake servo? Once those are clear, water should not be able to collect and trickle through the bulkhead.

Yeah, done all that. What worries me is that water drips/poors from the holes into/onto the heat proof matting around the exhaust etc. Seems to collect there and seep through the bulkhead. There are two bolts sticking out from the chases below the phelum chamber with nothing attached. Should there be a drainage system or something that has been removed? Any ideas? Gonna get it on the ramp on Saturday and have a proper look and report back. There is a gap in the welding between plates (circa 1/4 inch) that I sealed and it definitely lessened the leak.