Need plumbing advice....

G'day. I have a rental unit, and the tennant has reported a blocked toilet on several occasions in the last couple of weeks. The plumber my property manager uses (who unblocked it both times before with a plunger) told me this morning that he needs to dig up some concrete outside the toilet external wall and dig down to the sewer pipe to find the obstruction. He says that there is evidence that the concrete has been dug up here previously and due to the fact it is right next to the toilet outlet, he is convinced the problem lies there. He will also put in an I/O (????) pipe with a cap on it, so the area can be accessed more easily in the future.
Now my question is how long roughtly should this job take? He's quoted me $66 per hour which is OK, but won't give me a rough timeframe. I just want to make sure he isn't going to fleece me for a huge amount when the bill comes in!
The unit is about 25 years old if that helps regarding the possible sewer pipe material. As an aside, should the sewer be a Body Corp responsibility? I've tried getting onto the B.C manager, but she is away at the moment.
Thanks in advance.

Mate its hard to say how long it will take, depends on depth, whats buried in the ground, finding the fault etc. IO = Inspection opening, which will mean cutting out a section of the pipe if its earthenware or if its plastic and been installed correctly bringing up the IO thats already (or should be ) there on a soil pipe before it enters the building. Without looking at it, cut concrete, dig up, fix pipe, backfill, re-instate concrete, remove rubbish etc. I'd allow a day. As far as strata goes, it can be a grey area, some will cover it some will say its your responsibility untill it connects to the main drain, especially as your on the ground floor from what I can gather.

Had the same problem, it was a body corporate problem for me.

Unless they can come up with a real good reason why its not their problem I wouldn't be paying for the plumber.

My problem was caused by a tree miles away from the unit but only my unit was affected first as it was the closest to the tree.

Everything he told you sounds right to me.
I'd be hoping to get that all done in 2 - 4 hours.
Body Corporate should pay for this.

Help him dig it up if you're worried.

Sounds sensible, but I can give you the number of a reliable plumber who won't fleece you if you want it. Just send me a pm.