Welcome Eve,
There were a few Pettits who received medals for the Boer War. Including duplicated, they are:
A Pettit 86th Company Imperial Yeomanry
A Pettit 2nd Battalion The Buffs E K
A Pettit 1st Battalion Port Elizabeth Town Guard
A Pettit Victorian Mounted Rifles
A Pettit 3rd Battery Northamptonshire
A Pettit First Battalion The Border
A Pettit Victorian Mounted Rifles
A Pettit 3rd Battery Northamptonshire
A E Pettit 6th New Zealand Mounted Rifles
A E Pettit 6th New Zealand Mounted Rifles
A E Pettit Rand Rifles
A E Pettit 1st Battalion Scots Guards
Albert E Pettit 1st Battalion Scots Guards
Alfred Pettit Rosmead Town Guard
C Pettit 48th Company Imperial Yeomanry
C Pettit 2nd Battalion Northamptonshire
C Pettit Coldstream Guards
C Pettit Coldstream Guards
D Pettit 2nd Battalion The Buffs E K
D C Pettit Junior Willowmore Town Guard
D C Pettit Senior Willowmore Town Guard
E Pettit 2nd Battalion Northamptonshire
E S Pettit Fourth New Zealand
F Pettit Steinacker's Horse
F Pettit Army Service
F Pettit 3rd Battery Northamptonshire
F Pettit 3rd Battery Northamptonshire
G Pettit 3rd Battalion Grenadier Guards
G Pettit 3rd High Light Infantry
G Pettit 3rd Battalion Highland Light Infantry
G Pettit 18th Hussars
G Pettit 5th Victorian Mounted Rifles
G Pettit Victorian Mounted Rifles
G Pettit 2nd Draft Volunteer Service Company 2nd Northamptonshire
G Pettit 3rd Battalion Grenadier Guards
G Pettit 5th Victorian Mounted Rifles
G Pettit Victorian Mounted Rifles
George Pettit 5th 5th Victorian Mounted Rifles
H Pettit G Battery Royal Horse Artillery
H W Pettit Coldstream Guards
H W Pettit Coldstream Guards
J Pettit 1st Battalion King's Royal Rifle Corps
J Pettit 1st Battalion Kings Royal Rifle Corps
J Pettit 2nd Battalion The Buffs E K
J E Pettit
J E Pettit
J J Pettit Coldstream Guards
M Pettit Steytlerville Town Guard
N H Pettit 102nd Company Imperial Yeomanry
P A C Pettit 2nd South Australian Mounted Rifles
R G Pettit 4th Battalion Australian Commonwealth Horse
R J Pettit 19th Prince of Wales's Own Hussars
R J Pettit 19th Hussars
Robert Pettit 2nd Battalion The Queen's
Robert Pettit 2nd Battalion The Queens
S E Pettit Base Depot Imperial Yeomanry
S E Pettit 35th/53rd Squadron 11th Battery Imperial Yeomanry
Samuel Pettit Rosmead Town Guard
T Pettit 2nd Battalion Royal Irish Fusiliers
W Pettit 11th Battalion Imperial Yeomanry
W Pettit 4th Battalion Royal Dublin Fusiliers
W Pettit 2nd Battery Royal Field Artillery
W Pettit 11th Divisional Ammunition Column Prace Title-Vith Swante Divisional Ammunition Column Prace Slation Uoluheiter
W Pettit 2nd Battery Royal Field Artillery
W Pettit 4th Battalion Royal Dublin Fusiliers
Wm Pettit Steytlerville Town Guard
Y Pettit 2nd Battalion Royal Irish Fusiliers
If you go to this page
angloboerwar.com/unit-information/town-guards/2610-petg
and enter Pettit as the search term, you will see the 2 men listed, A and RJ.
There is not very much information about the PE Town Guard unfortunately.
Blayney should be easier to research as there are records for the CMR. There is 2172 Corporal W R V Blayney who was at Wepener and received the QSA and KSA.