Trouble at Allotment

Oh happy day! Our long awaited truckload of horse muck arrived! But then:
 
1.     He skillfully backed up to our carefully crafted retaining pen and said he would tip a little, then edge forward. In reality the whole lot whooshed out immediately, destroying the back of said retaining pen and seriously compromising our asparagus bed.
2.     When he tried to drive off our plot his wheels started spinning. He dug himself in deeper and deeper, despite our best efforts with bits of rug and paving slabs
3.     Eventually he managed it but his momentum carried him across two neighboring allotments, inflicting significant damage.
 
   
There must be a bon mot here somewhere about “looking gift horses in the mouth” and “where there is muck there is brass”. But all I can come up with is “Oh shit!!”