Brentford rejected MU's first offer, yes that's true. However, they receive another bid, which is getting improved from the first bid. They wanted MU to increase their bid, and they receive what they wanted. No reason not to call no to MU's offer as long as it's meet their asking price.
I have no clue what happen behind the scene, but i believe the talk is still ongoing between them and MU's representative. I hope an announcement to be rolling out in the coming days.
Even there is a rumor says a medical check up booked for Mbeumo.
Last season, Bryan Mbeumo performed quite well by scoring 20 goals and contributed 7 assists, I think its right players for central forward and Manchester United have huge ambition how to get deal agreement with Brentford. Finally quite though negotiation will announce until early of next month before Manchester United will prepare for pre season matches.
Mu bought Cunha fior 75 million. that makes sense if Brentford is also wanting the price close to the Cunha's price. Just look at the stats by both of players. It's reasonable if Brentford wanting more price from MU for Mbeumo.
I hope they to seal Mbeumo's signature very soon.