Estate agents can't get hold of vendors

[vegisaurus]

We are trying to arrange a 2nd viewing of a property with the view of putting an offer in. The first viewing was dead easy to arrange, and we were given a time slot during that initial phone call. I rang on Wednesday to arrange a 2nd viewing for Saturday, and the estate agents still haven't managed to get hold of the vendors (as of 13:30 today). Is this normal? I am worried they aren't actually keen on selling and even if they are, eluding EA phone calls at this stage might be a red flag further down the line!

My vendor accepted our offer and let us go back a second time but then stopped returning calls (including from the surveyor who wanted to arrange a time to go in). Needless to say we didn't end up in that house!

Could be various things honestly. I get called approximately thirty times a day by the agency I work with trying to push me into a shift so I don't answer my phone. I just go through my voicemails couple times a week.
If I've been on a night shift you'd be lucky to get a two day wait for a return call
Also if they have young children on summer holidays these phone calls get pushed way down the job list.

Might just be life getting in the way rather than a problem seller.

They might be on holiday - possibly in an area with no signal.

Or they have another offer that they are negotiating so don't want the bother of a second viewing if that is likely to be successful?

We had issues because our vendors worked odd shifts so didn't see each other much which has made any phone communication via EA quite lengthy as they both wanted input, even on viewing times etc.
Not saying that's the same here, but it's not always a disaster! They could've agreed some slots for first viewings, but need to make arrangements for second ones.

The estate agent may be telling porkies and isn't even trying, or they could have other potential purchasers for it who are also selling through them so possible double commission for them. They are a tricky bunch.

Go round to the house and put a note through the door.

They might possibly be on holiday at this time of year.